{"id":"F2006B02263","name":"AD/AL 250/51 Amdt 1 - High Pressure Fuel Control Filter Assembly - Modification","slug":"ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41493,"registerId":"commonwealth-F2006B02263-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/AL 250/51 Amdt 1 - High Pressure Fuel Control Filter Assembly - Modification","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 106 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nAllison Turbine Engines \\- 250 Series\n\nAD/AL 250/51\n\nAmdt 1\n\n  \n\nHigh Pressure Fuel Control Filter Assembly \\- Modification\n\n  \n6/83\n\nApplicability: All models 250-C20, C20B and C20J engines fitted with CECO P/N 6895173 or P/N 6896727 high pressure fuel control filter assemblies.\n\nDocument: Allison 250-C20, C20B and C20J Alert CEB-A-1144, Rev. 4.\n\nNote: FAA AD No. 82-13-03 refers.\n\nCompliance: For model 250-C20 and C20B : Forthwith.\n\nFor model 250-C20J : Not later than 1st August 1983.\n\nBackground: This Directive is issued to prevent possible metal contamination of the CECO Model MC-40 fuel control system power turbine governor which can result in power turbine rotor overspeed. It is raised in issue to Amdt 1 to include the model C20J as specified in Revision 4 of the Allison Document.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This amendment performs exactly as labelled — it expands the original directive's scope to include one additional engine model (C20J) based on updated manufacturer documentation. The core safety purpose (preventing fuel system contamination) remains unchanged."},"complexity_factors":["Single, specific technical modification to defined engine models","Only 2 part numbers and 3 engine variants in scope","Simple binary compliance structure (immediate vs. deferred deadline)","No nested exceptions, conditional logic, or cross-references to other legislation","Background and rationale clearly stated in plain language","References only one external technical document (Allison Alert CEB-A-1144 Rev. 4) and one related FAA directive for context"],"plain_english_summary":"This is an **Airworthiness Directive** — a mandatory safety order issued by Australia's Civil Aviation Safety Authority (CASA) that requires specific repairs or modifications to aircraft engines.\n\n**What it does:**\nOrders owners and operators of certain Allison 250-series turbine engines to modify their **high pressure fuel control filter assemblies** (a component that cleans fuel before it reaches the engine control system).\n\n**Who it affects:**\nAnyone operating aircraft with these specific engine models:\n- Allison 250-C20\n- Allison 250-C20B  \n- Allison 250-C20J\n\n**Only if** those engines have fuel filter assemblies made by CECO with part numbers 6895173 or 6896727.\n\n**What must be done:**\n- For C20 and C20B engines: **Immediately** (\"forthwith\")\n- For C20J engines: **No later than 1 August 1983**\n\n**Why it matters:**\nWithout this modification, metal particles could contaminate the fuel control system and cause the **power turbine to overspeed** — a dangerous condition that could lead to engine failure or damage. This amendment (Amdt 1) expands the original directive to include the C20J model after new safety information became available."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":true,"description":"The amendment expands the directive's scope by adding model 250-C20J to the list of affected engines. The AD text states it was raised to Amendment 1 to include the C20J model as specified in Revision 4 of the Allison document (Background; Document). Previously the directive applied to models 250-C20 and 250-C20B only."},"complexity_factors":["Narrow technical scope limited to specific engine models and two CECO part numbers (Applicability).","Different compliance dates for different models (immediate for C20/C20B; deferred deadline for C20J) (Compliance).","Dependence on an external manufacturer technical document (Allison Alert CEB-A-1144, Rev. 4) for the modification procedure (Document).","Reference to an FAA AD increases cross-jurisdictional cross-checking requirements (Note).","Operational implementation risks (sourcing parts, certified maintenance capacity and aircraft downtime) that vary by operator."],"plain_english_summary":"This AD mandates modifying the CECO high‑pressure fuel control filter assembly (parts 6895173 or 6896727) on Allison 250‑C20, C20B and C20J engines to prevent metal contamination of the MC‑40 fuel control and a possible power‑turbine overspeed. It affects owners, operators and maintenance organisations; work is required forthwith for C20/C20B and by 1 Aug 1983 for C20J. Operators bear costs and must follow Allison Alert CEB‑A‑1144 (and related FAA AD)."}},"importantCases":[],"_links":{"self":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification","history":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification/history","analysis":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification/analysis","conflicts":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification/conflicts","importantCases":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification/important-cases","documents":"/api/acts/ad-al-250-51-amdt-1-high-pressure-fuel-control-filter-assembly-modification/documents"}}